**EXAMPLE 3: ****Euler's equations for 2-D motion**

** **

** **

The uniform bar of mass *m* and length *l* is
released from rest from the horizontal position. Calculate the reaction at the
pin *O* as a function of the angle of
rotation.

**Solution:**

_{}

_{}

_{}

_{}

Substitution
of (1) and (2) and reorganization results in

_{}